Type 2 diabetes mellitus (T2DM) exhibited an even stronger association with risk of periodontitis among those who consumed few fruits and vegetables, noted the study authors, from the Harvard School of Public Health, Brigham and Women's Hospital, Dana-Farber Cancer Institute, and University of Puerto Rico School of Dentistry.

In one of the largest prospective investigations evaluating the association between periodontitis and T2DM, they analyzed data from the Health Professionals Follow-up Study (HPFS), an ongoing closed cohort that comprises 51,529 U.S. male health professionals, ages 40-75 (at baseline), who responded to a mailed questionnaire in 1986 to evaluate associations between diet, heart disease, and cancer.

The initial questionnaire collected data regarding diet, lifestyle behaviors, anthropometric measures, medication use, and medical and dental histories. Follow-up questionnaires have been mailed biennially since 1988, and more than 90% of the baseline population has responded to these additional questionnaires, the researchers noted.

"Given the high prevalence of periodontitis, the public health impact of an association between diabetes and periodontitis would be substantial among those affected by diabetes," they wrote.

Risk-factor data collection

Among the questions included on the biennial questionnaires were "Any professional diagnosis of diabetes mellitus?" and "Have you been professionally diagnosed with periodontitis with bone loss?"

When the researchers received a questionnaire reporting newly diagnosed diabetes, participants were sent a supplemental diabetes questionnaire designed to collect data on date of diagnosis, symptoms at the time of diagnosis, blood glucose levels, glycosuria, history of ketoacidosis at the time of diagnosis, and hypoglycemic medication.

In addition, data on several known risk factors for periodontitis and tooth loss, as well as potential confounders, were updated using the biennial questionnaires, with the exception of height, profession, race, and alcohol, fruit, and vegetable consumption, which were assessed from food-frequency questionnaires mailed every four years. Smoking status also was assessed over time.

At baseline, 35,247 dentate men who were free of periodontitis were included in the study, with more than 590,000 person years of follow-up and 3,009 self-reported periodontitis and 10,017 tooth loss events observed.

"At baseline, men with T2DM were more likely to report hypertension, were missing more teeth, consumed less alcohol, and were less likely to be dentists than men without," the researchers wrote.

In an age-adjusted model, risk of periodontitis was 39% higher in men with T2DM than in men without. In addition, T2DM was associated with a 22% increased risk of tooth loss compared with those without. And among men whose fruit and vegetable intake were below the population median, T2DM was associated with a 49% greater risk of periodontitis compared with the reference group, while the researchers found no association among men with fruit and vegetable intake above the median.

"In this study with 20 years of follow-up, T2DM was significantly associated with greater risk of self-reported periodontitis," the researchers wrote. "Furthermore, T2DM exhibited an even stronger association with risk of periodontitis among those who consumed few fruits and vegetables."

Individuals with diabetes may also be at an increased risk of tooth loss due to increased risk of periodontitis, they added.

"These results hold important public health implications due to the associations between periodontitis and cardiovascular disease and nutritional alterations associated with tooth loss," the study authors concluded. "Greater collaboration between diabetes care providers and dentists could be used to identify at-risk patients in both clinical settings."